Process of making blue sulfur dye.



ilnfrrnn Spares ATENT OFFICE.

ARTHUR, \VEINBERG AND RICHARD HERZ, OF FRANKFORT-ON-THE-MAIN,

GERMANY, ASSIGNORS TO LEOPOLD OASSELLA 6: (30., OF FRANKFORT- ON-TI-IIJM AIN, GERMAN Y.

5 PROCESS OF MAKING BLUE SULFUR DYE.

SPE IFL GAEEQN forming part of Letters Patent No. 693,633, dated February 18, 1902. Application filed August 24,1901. Serial No. 73,177- (Specimens-l T (tZZ whom, it may concern.-

Be it known that we, ARTHUR \VEINBERG and RICHARD I-IERZ, citizens of Prussia, and residents of Frankfort-on-the-Main, in the Province of Hesse-Nassau, Kingdom of Prussia, Germany, have invented certain new and useful Improvements in Blue Sulfur Dye and Processes of Making Same, of which the following is a specification.

1o lVe have found that by heating para-diah kylamido-para-oxydiphenylamins with sulfur and alkaline sulfids under certain conditions hereinafter specified blue dyestuffs of very bright shade result. In the manufacture of these coloring-matters great care must be taken that the temperature during the socalled melting process does not exceed much 140 centigrade, as otherwise to a large extent or almost exclusively bluish-black to blackish coloring-matters of less value result instead of the pure blue dyestuffs. In the production of this color on a technical scale it is, however, difficult to entirely avoid the formation of these blackish by-products, even if the above-mentioned conditions are carefully observed. It is therefore of importance to find a reliable method of completely separating the pure dyestuff from the blackish dyeing products. Such a method has been described in our application for Letters Patent Serial No. l2,2l2. Now we have found another process of isolating the pure blue dyestuif by precipitating it from its solution in alkaline sulfids by means of chlorids of metals the sulfids of which are soluble in water, such as sodium, potassium, calcium, barium. The impurities remain in solution generally in form of their leuco compounds. The process may be illustrated by the following exam- 0 pics:

First. Twenty-five kilos para-dialkylamidopara-oxydiphenylamin are heated with fifty kilos sufid of sodium and 12.5 kilos sulfur for twenty-four hours to about 11f centigrade.

The melt is then dissolved in six hundred liters water. One hundred and fifty kilos common salt are added, and the whole is well stirred for twelve hours. The precipitate is filtered off, well washed out with salt water, and pressed. For dyeing purposes it is best used in form of a paste, but may also be dried, preferably at a low temperature, and powdered.

Second. The melt obtained as described in the above example is dissolved in one thousand liters water at 30 centigrade. One hundred and twenty-five kilos of a solution of chlorid of calcium of 25 Baum are then added, and the whole is stirred for twelve hours.

In order to accelerate the precipitation, one o hundred kilos common salt may be added be-' sides. The precipitate, consisting of a limo compound of the pure dyestuff, which is rather difficultly soluble, and a certain quantity of insoluble organic and inorganic im- 5 purities, is filtered off, well washed out, and then redissolved by means of ten kilos sulfid of sodium and five kilos sodium carbonate in about seven hundred liters water of 50 centigrade. The solution is filtered in order to remove insoluble impurities, and the pure coloring-matter is precipitated from the solution by means of common salt.

The dyestuff possesses the properties described in our application for Letters Patent Serial No. 42,212.

Having now described our invention and in what manner the same is to be performed, what we claim is- 1. The process of producing pure blue sul- 8a fur dyestuffs by heating para-dialkylamidopara-oxydiphenylamin of the constitution with sulfur and alkaline sulfids and isolating the pure color from the crude melt by precipitating an aqueous solution of the latter 0 with chlorids of metals which form soluble sulfids.

2. The process of isolating the pure blue dyestuffs from the melt obtained from paradialkylamido-para-oxydiphenylamin, sulfur and alkalincsulfids,by precipitating the aqueous solution of the crude melt with calcium Province of Hesse-Nassau and Kingdom of chlorid,redissoiving the precipitate by means Prussia, this 6th day of August, A. D. 1901. of sodium sulfid and sodium carbonate, filter- ARTHUR WEINBERG. ing the solution thus obtained, and pi'ecipi- RICHARD HERZ.

5 tating the pure dyestu ff from the solution with Witnesses:

common salt. JEAN GRUND,

Signed at Frankfort-on-the-Main, in the CARL GRUND. 

